Rename trait HttpsStream -> ReadWrite and make it public

Also provide an example of how to use it.

src/ntls.rs

@@ -1,6 +1,6 @@
 use crate::error::Error;
 use crate::error::ErrorKind;
-use crate::stream::{HttpsStream, TlsConnector};
+use crate::stream::{ReadWrite, TlsConnector};
 
 use std::net::TcpStream;
 use std::sync::Arc;
@@ -11,11 +11,7 @@ pub(crate) fn default_tls_config() -> std::sync::Arc<dyn TlsConnector> {
 }
 
 impl TlsConnector for native_tls::TlsConnector {
-    fn connect(
-        &self,
-        dns_name: &str,
-        tcp_stream: TcpStream,
-    ) -> Result<Box<dyn HttpsStream>, Error> {
+    fn connect(&self, dns_name: &str, tcp_stream: TcpStream) -> Result<Box<dyn ReadWrite>, Error> {
         let stream =
             native_tls::TlsConnector::connect(self, dns_name, tcp_stream).map_err(|e| {
                 ErrorKind::ConnectionFailed
@@ -28,7 +24,7 @@ impl TlsConnector for native_tls::TlsConnector {
 }
 
 #[cfg(feature = "native-tls")]
-impl HttpsStream for native_tls::TlsStream<TcpStream> {
+impl ReadWrite for native_tls::TlsStream<TcpStream> {
     fn socket(&self) -> Option<&TcpStream> {
         Some(self.get_ref())
     }